Fluid pressure operated motor or pump



y 7, 1969 w. B. EASTON 3,446,153

FLUID PRESSURE OPERATED MOTOR OR PUMP Filed July 17, 1967 INVENTOR. MFA/s 3 EAJTQU United States Patent 3,446,153 FLUID PRESSURE OPERATED MOTOR 0R PUMP Wayne B. Easton, Eden Prairie, Minn. (400 Dain Tower, Minneapolis, Minn. 55402) Filed July 17, 1967, Ser. No. 653,918 Int. Cl. F01c l /1 0 US. Cl. 103-130 2 Claims ABSTRACT OF THE DISCLOSURE The invention relates generally to a low speed, high torque fluid pressure operated pump or motor of the gerotor type which has a valve which is rotatable in synchronism with the orbiting movement of the gerotor and particularly to new and improved means for driving the valve.

A main object of the invention is to provide a motor or pump of the type referred to having new and improved means for driving the valve of the device.

Other objects and advantages of the invention will become apparent from the following specification, appended claims and attached drawing.

In the drawing:

FIG. 1 is a longitudinal sectional view of a fluid pressure operated motor or pump embodying a new and improved valve drive mechanism taken on line 1-1 of FIG. 3;

FIG. 2 is a transverse sectional view taken on line 22 of FIG. 1; and

FIG. 3 is a transverse sectional view taken on line 33 of FIG. 1.

In the fluid pressure motor or pump illustrated there is provided a casing or housing made of several annularly and cylindrically shaped sections which are a valve casing section 2, a valve plate section 3 and a gerotor casing section 4. End cover plates 5 and 6 are provided for respective attachment to the valve casing section 2 and the gerotor casing section 4. Casing sections 2, 3, 4 and 6 are held together in axial alignment by a plurality of circumferentially spaced bolts 10. End cover plate 5 is attached to valve casing section 2 with a plurality of circumferentially spaced bolts 11.

Valve casing section 2 is provided with inlet and outlet ports 16 and 17 which would be reversed for operation of the pump or motor in the opposite direction.

The shape of gerotor casing section 4 is generally cylindrical and annular and has a plurality of internal teeth. An externally toothed star member 18 having at least one fewer teeth than casing section 4, which may be referred to as a ring member 4, has the teeth thereof in meshing engagement with the teeth of ring member 4. Star member 18 partakes of a hypocycloidal movement and the axis 40 thereof travels in a circular orbit about the axis 19 of ring member 4.

Valve casing section 2 has a generally cylindrical shape and with an axially extending bore 20 and a counterbore 22, both of which bores are concentric relative to the axis 19 of ring member 4. Inlet and outlet ports 16 and 17 communicate with the interior of bore 20 as shown in FIG. 1. Journaled in the bore 20 of valve casing section 2 in radial slidable engagement with bore 20 and axial slidable engagement with valve plate 3 is a cylindrically shaped valve 23. At the opposite end of the casing section 2 is journaled in bore 22 cylindrically shaped drive shaft collar member 25 which is in radial slidable engagement with casing bore 22 and axial sliding engagement with cover plate 5. Snap rings 26 and 27, or the like, are provided for respectively maintaining valve 23 and collar member 25 in their respective axial positions.

End plate 5 has a cylindrical bore 28 and collar member 25 has an axially extending shaft portion 29 which extends through and may be journaled in the bore 28, both bore 28 and shaft portion 29 being concentric relative to the ring axis 19. Shaft portion 29 is an input shaft if the device is used as a pump and an output shaft if the device is used as a motor.

With reference to FIG. 2, the gerotor casing section 4, which in effect is the ring member 4, has a plurality of internal teeth 36. Externally toothed star member 18, having at least one fewer teeth 38 than ring member 4, is disposed eccentrically in the chamber or space formed and surrounded by ring member 4. Star member 18 is movable orbitally relative to the ring member 4 with the axis 40 of star member 18 being moveable in an orbital path about the axis 19 of ring member 4. During orbital movement of star member 18 the teeth 38 thereof intermesh with the ring member teeth 36 in sealing engagement to form expanding and contracting chambers 42 which are equal in number to the number of teeth 36 of ring member 4.

With further reference to FIGS. 2 and 3 a vertical centerline or plane 44 represents the plane of eccentricity for the star member 18 for that particular position of the star member relative to the ring member 4. The plane of eccentricity 44 in effect rotates about ring axis 19 during relative movement between the ring and star member 4 and 18 at the orbital speed of the star member 18. Star axis 40 is in the plane 44 for all positions of the star member 18 relative to the ring member 4 and at any instant the position of the plane 44 indicates the eccentric position of the star member relative to the ring member. During orbital movement of the star member 18, and assuming the orbital movement is clockwise, the chambers 42 on the right side of the plane of eccentricity would be expanding and the chambers 42 on the left side would be contracting. If the device is used as a motor, fluid under pressure is directed to the expanding chambers and exhausted from the contracting chambers. If the device is used as a pump, fluid is sucked into the expanding chambers and delivered under pressure from the contracting chambers.

A wobble shaft is provided having connections with star 18, valve 23 and drive shaft collar member 25 as will be described. Star member 18 has a bore which is concentric relative to the teeth 38 and axis 40 thereof and is provided with a plurality of circumferentially arranged, axially extending teeth or splines 61. Valve 23 is provided with a generally axially extending opening 62 which will be referred to in detail further on. A bore 63 is provided in drive shaft collar member 25 and a cylindrically shaped pin 62 is provided which is attached to the collar member 25 and extends transversely across the bore 63.

Wobble shaft 50 extends between and mechanically connects star 18 and drive shaft collar member 25 in driving relation. The right end 66 of shaft 50 is frustospherically shaped with an effective diameter which is the same as the diameter of star bore 60 and is provided in a known manner with a series of splines equal in number to the plurality of star spline-s 61. The spline connection between the right end 66 of shaft 50 and star 18 is a known form of universal joint which permits shaft 50 to transmit rotational driving forces or torque from star 18 to the left end of shaft 50 while assuming any angle within practical limits relative to star axis 40. The left end of shaft 50 has a slot 68 which extends diametrically thereof for receiving the pin 60, the width of slot 68 being approximately equal to the diameter of pin 64 so that there is provided a close fitting, sliding engagement between pin 64 and slot 68. This pin and slot connection is also a known form of universal joint which permits shaft 50 to transmit rotational driving forces or torque from the the star member 18 while the left end of the wobble shaft may assume any angle within practical limits relative to the axis 19 of shaft 29.

Star member 18 is eccentrically disposed relative to ring member 4, as mentioned above, and the wobble shaft 50 is thus always in a cocked or tilted position relative to valve 23, which has the same axis 19 as ring member 4, and to the axis 40 of star member 18. In operation a star member 18 having six teeth will make one revolution about its own axis 40 for every six times the star member orbits in the opposite direction about the axis 19 of the ring member 4. Thus, the right end 66 of wobble shaft 50 has both orbital and rotational movement in common with the star member 18 while the left end of the wobble shaft 50 has only rotational movement in common with shaft 29. When the device is utilized as a pump, star member 18 will be gyrated by a turning force applied to shaft 2 9 which is transmitted to star member 18 through the wobble shaft 50. When the device is used as a motor, the force created by the rotation of star member 18 about its own axis 40 will be transmitted through wobble shaft 50 to shaft 29 to cause turning of shaft 29.

Wobble shaft 50 has a cylindrical surface 70 which is colinear with respect to the geometric axis 71 of shaft 50 about which shaft 50 is rotatable. Wobble shaft axis 71 is at all times disposed in the plane of eccentricity 44 and describes a conical path about ring member axis 19 during relative movement between the star and ring members. In effect, wobble shaft axis 71 describes the conical path referred to in synchronism with the orbital movement of star 18 and wobble shaft 50 rotates about its axis 71 in synchronism with the rotational movement of the star 18.

As illustrated, valve 23 has an axially extending, slot shaped opening 62having parallel sides 74 and 75, the parallel sides of the slot being equally spaced from the ring member axis 19 and being spaced apart a distance approximately equal to the diameter of wobble shaft 50. Wobble shaft 50 engages the parallel slot surfaces 74 and 75, and as wobble shaft 50 is inclined relative to ring axis 19, the circumferential position of valve 23 is in effect indexed relative to the plane of eccentricity 44 and the parallel slot surfaces 74 and 75 are at all times symmetrically disposed relative to the plane 44 during relative movement between the star and ring members. As illustrated, there are two index positions for the valve 23 which are displaced 180 degrees from each other and which provide for a reversal of operation regardless of whether the device is operated as a pump or a motor.

As indicated in FIGS. 1 and 3, the wobble shaft 50 engages valve slot walls 74 and 75 along lines 80 and 81 which are parallel to each other and the wobble shaft axis 71 and, when considered as a pair of lines, are spaced from the ring axis 19 in the direction of the star axis 40. In the drawing the indicated lines 80 and 81 are not a part of the construction but only indicate lines along which there is physical contact or engagement between wobble shaft 50 and valve 23.

As the lines of contact 80 and 81 are eccentrically disposed relative to ring axis 19, the conical motion of the wobble shaft 50 acts as a crank and causes rotation of valve 23 in synchronism with the orbital movement of star 18. Wobble shaft 50 also rotates about its own axis 71 in synchronism with the rotational movement of star 18 but this rotational movement is not transmitted to the valve 23.

It is obvious that the valve opening 62 could have other forms such as the form of an inclined hole having a diameter approximately equal to the diameter of wobble shaft 50 and having an axis which would be coaxial with the axis 71 of wobble shaft 50. Regardless of the particular form that such a hole might take, it is only of importance with respect to the present invention that the hole have a surface or surfaces which would contain the lines and 81 so as to permit abutting engagement between wobble shaft 50 and the valve 23 as described above.

With regard to the fluid passages for the valves 23 0f the pump or motor illustrated, valve 23 and easing sections 2 and 3 are provided with fluid passages in a known manner through which fluid is conveyed from the port 16 or 17 to the chambers 42 of the gerotor and returned to the other of the ports 16 or 17 Port 16 or 17 will be the inlet, and the other the outlet port, depending on the direction of rotation desired for shaft 29. During orbiting of star 18 about ring member axis 19, the star rotates in the opposite direction about its own axis 40 at a slower speed. The ratio between the orbiting and rotating speeds is dependent upon the ratio between the ring and star member teeth. If that ratio is seven to six as illustrated herein the rotating speed of the star will be one-sixth of its orbiting speed. By reason of the shaft connection between star 18 and valve 23, valve 23 rotates at the same speed and in the same direction as the orbiting direction of the star. Valve 23 is of the high speed type and functions to supply and exhaust fluid to and from the gerotor at the orbiting frequency of the star.

Referring to the fluid passage arrangement, valve plate 3 is provided with a set of circumferentially arranged, axially extending passages 85 which extend from casing bore 20 to the respective junctions between the ring member teeth 36 for supplying and exhausting fluid to and from the gerotor chambers 42. Valve 23 has two axially spaced annular channels 86 and 87 which are axially aligned with ports 16 and 17 and in respective fluid communication therewith. Assuming for purposes of illustration that port 16 is the inlet port, valve 23 has a fluid feeding passage 88 which is illustrated as an are shaped recess in the end face 89 of valve 23 on one side of the plane of eccentricity 44 and is connected to the annular channel 86 and the inlet port 16 through a passage 90 in valve 23. Valve 23 also has a fluid exhausting passage 93 which is illustrated as an are shaped recess in the end face 89 of valve 23 on the opposite side of the valve 23 and the plane of eccentricity 44 and which is connected to the annular channel 87 and the outlet port 17 through a passage 94 in the valve 23. Fluid feeding and exhausting passages 88 and 93 are separated along the plane of eccentricity 44 by lands 96 and 97.

Upon rotation of valve 23, fluid feeding passage 88 and fluid exhausting passage 93 successively register in fluid communication with valve plate passages 85. If the fluid pressure device is functioning as a motor or a pump, fluid may be introduced through port 16 from where it would flow into annular channel 86 of valve 23 and through passage 90 to fluid feeding passage 88, through certain of the valve plate passages 85 to the expanding chambers 42. At the same time fluid from the contracting chambers 42 flows through other of the valve plate passages 85 to the fluid exhausting passage 93 of valve 23, through valve passage 94 to the annular channel 87 and out the outlet port 17.

If desired, as a modification, valve plate 3 could be omitted in which case the fluid feeding and exhausting passages 88 and 93 of valve 23 would have direct fluid communication with the expanding and contracting chambers 42 of the gerotor. With that type of construction the valve lands 96 and 97 would have to be of suflicient circumferential width so that short circuiting of the fluid between the expanding and contracting chambers 42 would be avoided. An advantage of this construction, however, would be that valve 23 would be positioned closer to the gerotor and thus the effective crank arm between wobble shaft 50 and valve 23 would be correspondingly increased.

While one embodiment of the invention is described here, it will be understood that it is capable of modification, and that such modification, including a reversal of parts, may be made without departure from the spirit and scope of the invention as defined in the claims.

What I claim is:

1. A rotary fluid pressure device comprising a casing having fluid inlet and outlet means, a ring member defining a chamber and having a plurality of circumferentially spaced internal teeth symmetrically disposed relative to the axis of the ring member, a cooperating externally toothed star member having fewer teeth than said ring member and having an axis disposed eccentrically and in parallel relation to the axis of said ring member, the axis of said star member being at all times during relative movement between said members in a plane which rotates about the axis of said ring member, said star member having rotational movement about its own axis and orbital movement about the axis of said ring member with the teeth of said members intermeshing in sealing engagement to form expanding chambers on one side of said plane and contracting chambers on the other side of said plane during relative movement between said members, a drive shaft rotatably disposed in said casing, a valve rotatable disposed in said casing between said star member and said drive shaft, said valve having a generally axially extending opening, a wobble shaft extending through said opening in said valve for connecting said drive shaft to said star member to effect rotation of said drive shaft in synchronism with said rotational movement of said star member and for connecting said valve to said star member to effect rotation of said valve in synchronism with said orbital movement of said star member, said wobble shaft having its axis disposed in said plane while describing a conical path about the axis of said ring member, said wobble shaft having a cylindrically shaped surface portion concentrically arranged relative to the axis of rotation thereof with said surface portion having contact with said valve opening on both sides of said plane, said valve having fluid feeding passage means on one side of said plane in fluid communication with said fluid inlet means and fluid exhausting passage means on the opposite side of said plane in fluid communication with said fluid outlet means to effect communication between said inlet means and said expanding cells on one side of said plane and between said outlet means and said contracting cells on the other side of said plane during rotation of said valve.

2. A rotary fluid pressure device according to claim 1 wherein a valve plate is fixedly attached to said casing and is disposed between said valve on one side and said star and ring members on the other side, said valve plate having a plurality of a circumferentially arranged axially extending holes extending from said fluid feeding and exhausting passage means of said valve to said expanding and contracting chambers.

References Cited UNITED STATES PATENTS 3,270,681 9/1966 Charlson 103-130 3,272,142 9/1966 Easton 103--130 3,288,034 10/1966 White et al. 91-56 JULIUS E. WEST, Primary Examiner.

US. Cl. X.-R. 91-56; 230- 

